Friday, July 15, 2011

Unathorize a DHCP server with a "The parameter is incorrect." error

After a migration of DHCP from one server to another I found my self trying to unathorize the old server. One way to do it is to select the Server in the DHCP Tool. Then click "Action" on the menu bar and then click "unauthorize." You can accomplish this alos by right-clicking on the server as well and clicking "Unauthorize."
Upon doing this I discovered an odd problem. After doing this you get the "Are You Sure" prompt. Upon clicking "Yes" then it returns the error below "The parameter is incorrect":
 
After trying a couple of different things it still stuck. During my migration I had used the command prompt and the netsh tool. So I went hunting on how to unauthorize a server. My search led to some interesting information. You can follow this link to read Microsofts KB explaining how to do what we will do. http://support.microsoft.com/kb/303351

The DHCP server information is retained in active directory. So if you have ever uninstalled DHCP, removed a server, or any other such action without unathoirzing the DHCP server they are still listed in AD. You can read more about why it's listed in AD and so on here.

To see what DHCP servers are currently authorized in DHCP open a command prompt and run the following command "netsh dhcp show server". Upon doing this I noticed a server I had used before that was no longer around. These results will give you two pieces of information you will need to deuathorize the servers from AD. The server name and Address.

Run the following command with your servers information filled in"netsh dhcp delete server [servername] [server ip address]". It should give you a command completed successfully if everything went well. You can re-run the show server command to see if it worked.

I used this command to remove the old server  that was no longer used as well as to remove(unauthroize) the server that was giving me the error. Upon doing this I jumped back into the DHCP tool to see if it recognized my change.

Upon right-clicking the server it was showing me the optin to "authorize" the server. This confirmed that netsh worked. I was then able to remove the DHCP role from my server.

6 comments:

  1. Thanks. I found that I needed to use the netsh command as the dhcp server originally had a slightly different name in active directory.

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  2. Worked like a champ. Saved my bacon! Thanks brother!

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  3. I set up a failover DHCP server before teaming NIC's, so it was in AD with the wrong IP address. This is exactly what I needed for the DHCP servers to see each other! Thanks!!

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  4. Thanks man, helped me remove a stubborn old server!

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  5. Thanks, was having problems removing a server as well, very helpful

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  6. worked perfectly thankyou!

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